auxiliary support (support auxiliaire, masc., or support secondaire, masc.)

The framework over which a canvas is stretched.

Note: It usually refers to a stretcher or a strainer. It could also refer to a secondary support material such as a rigid board or stretched fabric that provides additional support to the primary support (see Figure 1).

A rigid board attached to the back of an auxiliary support or frame to protect the painting.

bevel (biseau, masc., or chanfrein, masc.)

Angled face of a stretcher or strainer bar (on the canvas side).

Note: A bevelled edge (see Figure 1) prevents the canvas from coming into contact with the stretcher bars when ground and the paintlayer are being applied. In the long-term, it may also help to prevent a stretcher mark on the canvas or a crack from developing on the completed painting.

Note: Bulges on the face of a canvas can be caused by blows to the back of an unprotected canvas. A bulge can also be caused by sustained pressure on the canvas, e.g. from debris lodged between the auxiliary support and canvas, from an object leaning against the back of the canvas or from extra material (e.g. excess glue) caught between a primary and auxiliarysupport.

See also: cockling, corner draws, dent

butt joint (joint abouté, masc.)

A joint formed by two lengths of wood meeting without any interlocking element cut into the adjoining pieces.

Note: Butt joints may be square-ended, with the end of one piece meeting the edge of the other at 90°. Butt joints may also be mitred, with both ends cut to meet at a 45° angle (see Figure 2).

A wavy deformation in the support, usually associated with works on paper.

Note: In paintings on canvas, cockling or rippling is often seen along the edges of a painting and may be the result of inadequate or uneven tacking of the canvas to the auxiliary support combined with relaxation of the materials of the painting and fluctuations in humidity.

A mix of materials, traditionally hide glue, rosin, linseed oil and whiting (chalk or gypsum), that can be pressed and shaped to make moulded ornamentation on frames.

Note: Compo ornaments are applied on a frame’s wood surface and are often gilded.

Other term: composition

composite support (support composite, masc.)

A support composed of two or more materials, such as canvas (primary support) attached to cardboard (secondary or auxiliary support).

See also: artist’s board, auxiliary support, rigid support, support

composition

See: compo

compressed wood board (panneau de bois aggloméré, masc.)

A rigid panel engineered from wood fibres, particles or flakes that are compressed under heat and pressure with bonding agents such as wax, resin and other additives in order to produce specific properties for particular end uses.

Note: Compressed wood boards that have been most commonly used as painting supports are high-density fibreboards (hardboard), medium-density fibreboards (MDF) and low-density fibreboard, such as beaverboard. Particleboard is also a type of compressed wood board.

See also: hardboard, panel

concentric cracks (pl.) (craquelure circulaire, fem.)

Mechanical cracks in a roughly circular or cobweb-shaped pattern that are caused by a blow to or pressure on a painting.

Note: Draws also develop along the edges of a painting where there is cockling. Draws occur during exposure to low relative humidity (e.g. during winter in cold climates with central heating) and may disappear when moderate relative humidity returns.

Other term: draws

See also: bulge, cockling, dent

crackle (pl.)

See: cracks

cracks (pl.) (craquelure, fem.)

Surface or deep checks in one or more of the varnish, paint or ground layers.

Note: Cracks are caused by a combination of mechanical forces and the response of the paint, ground and support layers to relative humidity fluctuations, periods of low relative humidity and low temperatures.

A thin protective strip of wood, metal or plastic attached to the sides of a painting and extending above the paint layers.

Note: Edge-strips on the four sides are used to isolate the paint surface from the rabbet or glazing2 of the frame (see Figure 3). However, in many circumstances using padding along the rabbet is now preferred.

A reinforcing material, usually tissue paper, temporarily attached with adhesive to the surface of a painting in order to secure loose paint particles and protect the paint layer during certain conservation treatments.

Mechanical cracks in a pattern resembling a feather which are caused by a line of contact against the back of the painting (e.g. a scrape) or a glancing contact on the canvas with a hammer when keying out.

A transparent layer (oil or resin-rich; usually pigmented) applied by an artist on the surface of a painting.

Note: The glaze can be composed of a single or multiple layers.

glazing1 (verb) (vitrage, masc.)

The action of fitting a protective sheet of glass or acrylic into a frame, separated from the painting by a liner, spacer or an edge-strip.

glazing2 (noun) (vitre de protection, masc.)

A protective sheet of glass or acrylic placed into a frame and separated from the painting by a liner, spacer or an edge-strip.

See also: edge-strip, rabbet

gouge (entaille, fem.)

The damage caused when material has been removed or dug out of a painting’s surface, support, auxiliary support, frame or another element of the artwork.

grime (encrassement, masc.)

A disfiguring deposit on or ingrained into the surface of a painting.

Note: Grime is often a combination of airborne soot, nicotine, cooking oils, smudges or finger and palm marks.

See also: accretion, surface dirt

ground (préparation, fem., apprêt, masc., or enduit, masc.)

An opaque white or coloured preparation layer applied to the support as a base for the paint layers.

Note: Grounds were traditionally composed of chalk or white lead combined with glue or oil. Today, grounds formulated with modern pigments and acrylic medium are common.

Other term: priming

half-lap joint (assemblage à mi-bois, masc.)

A type of lap joint where two wood pieces of equal thickness are made to fit together by reducing half the thickness of the wood at the joint site (normally a corner joint) and then overlapping the two thinned sections to produce a flush surface (see Figure 4).

New paint applied on areas where original paint has been lost or abraded.

See also: inpainting, overpaint

inpainting (retouche2, fem.)

In restoration, the application of new paint on areas where original paint has been lost or abraded.

Note: “Retouching” used to sometimes mean inpainting, but it was also used to imply an unnecessary and damaging change to the original painting (overpainting). Today, the term “overpainting” is preferred for this concept.

A small piece of wood inserted into slots at the corners or joints of an auxiliary support to make the joints adjustable.

Other term: wedge

key out (régler la tension de la toile)

To expand a stretcher corner.

lacuna

See: loss

lap joint (joint à recouvrement, masc.)

A joint made at the intersection of two pieces of wood that are partially cut away so that they overlap smoothly when placed partly over one another (see Figure 4).

Note: How the cut is made and where the joint occurs determines the type of lap joint. Two examples include a joint at a corner where two planks meet at right angles (half-lap joint) and a joint near the middle section of one of the planks (cross lap joint).

The inside portion of a frame that borders a painting and is made separate from the frame.

Note: Liners are attached to the frame usually with nails or staples.

lining (rentoilage, masc., or doublage, masc.)

The process of providing a new fabric support to the back of a painting on canvas.

Note: This support may be attached to the original fabric support with adhesive or may just be in contact with it. Attaching a new fabric to the back of a painting that has previously been lined is called relining.

See also: loose lining, stretcher bar lining

loose lining (toile de soutien, fem.)

A fabric that is stretched directly behind, but not attached to, a painting on canvas and that provides additional support and protection to the painting.

Other term: blind lining

See also: lining, stretcher bar lining

loss (lacune, fem., or manque, masc.)

An area where paint or the paint layer and ground are missing because of damage or deterioration.

Other term: lacuna

luting

See: fill

marouflage (marouflage, masc.)

The process of attaching a canvas to a rigid surface (e.g. a wall, a panel).

mechanical cracks (pl.) (craquelure de tension, fem.)

Cracks that are caused by movement or excessive stress in various layers of a painting and that have sharp edges.

Note: Mechanical cracks may be distributed over a painting or may be restricted to one area associated with a blow or pressure to the back or front of the painting. These cracks are often described by the pattern they create.

Paint that was not applied by an artist and that covers original paint.

Note: Overpaint was often used to change a painting’s image or to hide damage and usually covered more original paint than was necessary.

See also: inpaint, inpainting

paint (peinture, fem.)

A film-forming material composed of pigment or dye and a binder, such as oil, acrylic, resin, gum or glue.

See also: binder, paint layer, pigment

painting medium

See: medium2

paint layer (couche picturale, fem.)

One or several colour layers which make up the paint.

See also: binder, paint, pigment

panel (panneau, masc.)

A rigid primary or secondary support.

Note: Traditionally, a panel was a wooden board or a number of boards joined together. The term has now broadened to refer to wood-based supports, such as compressed wood boards and plywood. Other rigid materials, such as aluminium honeycomb-core supports and aluminium/polyethylene boards, can also be referred to as “panels.”

See also: compressed wood board, hardboard

pentimento (repentir, masc.)

An underlying design element seen through the surface paint layer, where an artist made a change in composition while painting that work of art.

Note: Oil paints become more transparent with age, so underdrawings or design elements executed in a preliminary composition may become visible.

Note: pentimenti: plural.

pigment (pigment, masc.)

Finely divided coloured particles that, when combined with a medium, form paint.

See also: binder, paint, paint layer

plain pattern

See: plain weave

plain weave (armure toile, fem.)

A weave pattern seen in canvas paintings where one weft thread is woven alternately over and under the warp threads (see Figure 7).

A solution, emulsion or gel applied to raw canvas or another painting support before the ground layer is applied in order to protect the canvas fibres from the oil medium and reduce the absorbency of the support.

Lining that does not require a painting to be removed from its stretcher or the use of adhesives.

Note: Lining fabric is inserted between a painted canvas and its stretcher’s crossbars, then stretched and attached to the back of the main (outer) stretcher bars.

Other term: cami-lining (former des., avoid)

See also: lining, loose lining

stretcher crease

See: stretcher mark

stretcher garland

See: tension garland

stretcher mark (marque du châssis, fem.)

A line of cracks or deformation in a painting’s surface that follows along the inside edges of the stretcher or strainer bars.

Note: The marks may result from repeated contact of the canvas with sharp-edged or inadequately bevelled stretcher or strainer bars or from the influence of the differing environments behind the canvas at the inner edges of the bars.

A solution of resin dissolved in a solvent, which dries to form a transparent film.

Note: Varnish is usually used as a final surface coating over a finished painting to even out the gloss, to saturate the colours and to protect the paint. The most common varnishes consist of natural resins such as mastic, dammar or copal. Recently, various synthetic resins have been used.

See also: surface coating

warp1 (chaîne, fem.)

The set of threads in a fabric that run parallel to the selvedge edge.

See also: plain weave, twill weave, weave, weft

warp2 (gauchissement, masc.)

A deformation, such as a bend or curve, in a rigid or semi-rigid material.

See also: deformation

wear (usure, fem.)

A change in the surface from the effects of abrasion.

See also: abrasion, rubbing, scraping, skinning

weave (armure, fem.)

The pattern created by the weft threads overlapping the warp threads in a woven fabric.

See also: plain weave, twill weave, warp1, weft

wedge

See: key

weft (trame, fem.)

The set of threads in a fabric that run at right angles to the selvedge edge.

See also: plain weave, twill weave, warp1, weave

white card

See: white cardboard

white cardboard (carton blanchi, masc., or carton blanc, masc.)

A paper-based board produced in various thicknesses, usually from multiple layers of paper fibres, which is normally used as a support for smaller paintings.

Other term: white card

wrinkles (plissement, masc.)

Puckers or ridges and furrows in a paint or varnish film that occurred during drying.